OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
n=44; sigma#(44)=18 and sigma#(45)=18.
MAPLE
with(numtheory);
A222088:=proc(q)
local a, b, c, d, j, n, t, v;
d:=1;
for n from 2 to q do
a:=ifactors(n)[2]; b:=nops(a); c:=0; v:=0;
for j from 1 to b do if a[j][1]^a[j][2]>c then c:=a[j][1]^a[j][2]; fi; od;
a:=op(sort([op(divisors(n))])); b:=nops(divisors(n));
for j from 1 to b do v:=v+a[j]; if a[j]=c then break; fi; od;
if d=v then print(n-1); fi; d:=v; od; end:
A222088(1000000);
MATHEMATICA
s[n_] := Module[{sum=0, L=1}, Do[sum+=d; L = LCM[L, d]; If[L == n, Break[]], {d, Divisors[n]}]; sum]; s1=1; seq={}; Do[s2=s[n]; If[s1==s2, AppendTo[seq, n-1]]; s1=s2, {n, 2, 10^4}]; seq (* Amiram Eldar, Nov 05 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Feb 13 2013
STATUS
approved